S42 refers to a specific section of the UK's Freedom of Information Act 2000, which allows public authorities to refuse requests for information if it relates to law enforcement and could compromise investigations. This provision aims to protect sensitive information that, if disclosed, might hinder the prevention or detection of crime. The S42 exemption is part of a broader framework that balances the public's right to know with the need for confidentiality in certain situations. It is often invoked by agencies such as the Police or Crown Prosecution Service when responding to information requests that could impact ongoing cases.